How to Braze Sheet Metal

By Thomas James ; Updated April 12, 2017
Brazing is used to construct metal objects such as pipes.

Brazing is a technique for joining pieces of metal together by filling the join between the two metal pieces with a molten intermediary metal. Brazing is distinguished from welding because it uses an intermediary material, usually a copper-zinc alloy, to join the two metal pieces rather than melting the pieces themselves. Brazing requires less energy than welding and can be used to join dissimilar metals.

Wipe the areas on the metal pieces that will be joined with the emery cloth so the surfaces are free from dust and grease.

Mix a small amount of flux with water to form a paste. Apply this paste to the areas on the metal pieces that will be joined using the brush.

Place the two metal pieces on the rotating table. Rest them on top of pieces of firebrick so they are held above the surface of the rotating table. Ensure they are held in the appropriate position.

Activate the compressor and press the button to ignite the pilot light to turn on the blowtorch.

Apply the flame of the blowtorch to the metal pieces for a brief period so that the water in the flux evaporates and the metal pieces are warm.

Apply the flame so that the tip of the central blue part of the flame nearly touches the metal. Move the flame back over the area to be joined until it turns red.

Hold the brazing rod against the area to be joined. The rod should melt and the brazing metal should flow into the gap between the two pieces. Allow the pieces to cool slowly.

Things Needed

  • Emery cloth
  • Flux
  • Water
  • Brush
  • Rotating table
  • Firebrick
  • Blowtorch
  • Brazing rod
  • Metal tongs
  • Leather gloves
  • Leather apron
  • Goggles

Warning

Use leather gloves and aprons to prevent harm from accidentally touching hot metal. Wear goggles to protect from splashes of molten metal. Always use metal tongs to manipulate hot metal pieces.

About the Author

Thomas James has been writing professionally since 2008. His work has appeared on the science-fiction blog Futurismic. He writes about technology, economics, management, science fiction, politics and philosophy. James graduated from Trinity Catholic School and holds A-levels in physics, maths, chemistry and an AS-level in English language.